CB4 (Ceiling/Sidewall) is designed to install hands free. You no longer have to hold grilles in place while trying start your trim mounting screws. Just slide your CB4 register grille cover in and the patent pending clip-design holds the CB4 in place leaving your hands free to install the trim mounting screws. Finish the Job in seconds not minutes. The clips hold the CB4 in place and align the mounting holes perfectly to fit with the innovative SPEEDI-BOOT mud ring frame. This precise fit improves air flow and your comfort level. CB4 also comes in other sizes and styles which are available on this web site or by special order. CB4 stays in place and reduces frustration and headaches. You will be amazed at how easy installing CB4 is and how much time/labor you will save. Grille trim screws must be installed for secure installation. (CB4 can be installed in a non SPEEDI-BOOT installation).